GalFisk Posted April 3, 2008 Posted April 3, 2008 I have a similar six ton press, and the material is very heavy. The beams are at least 5mm steel, maybe more (going by memory).The density you can get with a certain press depends on the puck size, in a weaker press you may need to make smaller pucks. What size pucks are you making, Swede?
Bonny Posted April 4, 2008 Posted April 4, 2008 I just pressed some BP using the passfire 'multi puck" idea...what a bunch of shit.I pressed 500g (dry weight) BP with 10% water in a 3" ABS pipe with my 12 ton jack. The pipe was 6" long and I made 5 pucks. I used cut up pop can discs as spacers. Anyway, I blew 2 hose clamps out of 5 off while pressing and the pipe bulged like crazy. I had to cut it apart with a hacksaw to get my pucks out...The Al discs were reduced to fragments, hard to believe, but it happened. I'll add some pics as son as the old lady gets home with the camera. Maybe I'm superhuman to press so hard... Anyway, I think I'll go back to pressing without a slot in the pipe and press the pucks out as I did before...takes longer but never this much BS headache.
Bonny Posted April 4, 2008 Posted April 4, 2008 ? Where's the inner sleeve ? The method on passfire uses no inner sleeve, only a split pipe with hose clamps. I won't be doing it that way again. I will try and calculate density of the BP for curiosity's sake.
Swede Posted April 4, 2008 Author Posted April 4, 2008 I have a similar six ton press, and the material is very heavy. The beams are at least 5mm steel, maybe more (going by memory).The density you can get with a certain press depends on the puck size, in a weaker press you may need to make smaller pucks. What size pucks are you making, Swede?Galfisk, I am brand new at this stuff, and have never pressed in any quantity. The little pellets I pressed were purely experimental, and amounted to just a few grams. The press I own has been in my shop for many years, used for machine shop work. I didn't buy it for BP, but I think for the serious Pyro, it is a superb investment, because you can do so much more with it. Think rockets! as well as the BP. And a 5-foot floor model will run maybe $80 brand new, on sale. One thing I wish I had done... I think a model with a pressure gauge on it is worth the extra $$ because it will allow you to be completely consistent, batch to batch. Otherwise, you are guessing. The push they give is so powerful and smooth, and I think the important part is that unlike a hammer, you can leave the pressure ON for hours if need be. I think that may be much of the secret - a sustained pressure, not a temporary one. Like Galfisk says, the smaller the pucks, the more compression you are going to get, so it is always possible with a small press to simply make more, smaller disks.
marks265 Posted April 5, 2008 Posted April 5, 2008 When I press my pucks I use a hydraulic cylinder that I took apart and cut down for a mold. When I take a loaded cylinder to the press I set it on a piece of chip board. I begin pressing slowly, some water will ooze out which looks mostly clear. Then I slowly lay into it and press on the 1-1/2" piston with all 12 tons until the cheap press flexes and says "Are you sure?" a couple minutes later I say "yea" and pump on the handle a little more! The cylinder spends about 10 minutes under pressure and then I take it out. The chipboard was actually fairly dry under the puck but additional moisture soaked up beyond the cylinder going outwards into the chipboard. I weighed the pucks immediately after pressing and recorded each reading. After about 3 days I reweighed the pucks and each of them lost about a gram in weight (water loss via natural evaporation). Off the top of my head these pucks had an average weight of about 45 grams. I also know that the water most definately (sp) carried some KNO3 away but the results make me most happy! This is how I get my 1.8+ densities. 1.8 maybe a little dense for other peoples liking but it does what I need for now and keeps things simple. KISS is an old saying "Keep It Simple Stupid" So I KISS my press and dig elsewhere. If you try a puck and it does not burn fast enough try a smaller puck size maybe. So yea I'm not happy with the complicated Passfire thing either but what they had to offer got me thinking about what would work for me! My 2 worth!
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